The present invention provides a prealarm system for an anti-theft alarm to provide a pre-alerting signal by detection of a moving object or vibration.
Generally each anti-theft device includes one or more detectors of the same or different types, and the sensitivity of such detectors can be adjusted to provide the best anti-theft effect. However, if the sensitivity is too low, the detector can't detect invasion. If the sensitivity is too high, a slight and unintentional shock can enable the alarm and thereby bring the inconvenience of a false alarm.
The instant invention provides a prealarm system for an anti-theft alarm which has the following features:
(1) Sensitivity of the burglar-proof alarm can be adjusted without generation of the normal siren alarm during assembly, to avoid unnecessary noise;
(2) Upon an attempt to break into the protected area, the system can generate a prealarm at the very beginning of the attempt, to stop any further invasion;
(3) It can warn others not to attempt to invade cars or buildings having the instant system installed; and,
(4) Its owner can check for sensibility of the alarm by using the prealarm system.